During the production of a device, it often turns out that due to too small diameter of ribbon cable wires or another reason, some of the fittings crimped on it, made a poor contact. Because the faults are revealed in a way that hinders the detection, a simple test to pass the measure is unreliable and slow.
The device described here is a simple acoustic tester that checks the cables, that have to be sure because of the complexity and price of the equipment in which they work.
How to check:
The device is projected for 10-wire cables. The tested cable has to be plugged by finished cubes into connectors in the testes. The sound would come out the speaker. Break in one of the wires would be manifested by a decrease in pitch. The more wires are damaged, the more the sound is decreased. By moving the cable, even the slightest uncertainty in the contact can be detected.
Scheme:
I'm afraid that in the era of microntrollers such approach is quite obsolate (it sounds like solution from the 70's). I agree it will work but it will also require musical skills from the operator. You can make with single microcontroller tester of the 10 pins which is fast emough and is much more reliable.